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gems
Roger Weller,
geology instructor
wellerr@cochise.edu
Diamonds,Man-Made
Crystal Roe
Physical Geology
Fall 2005
Man-Made
Diamonds
History
On February 15, 1955 General
Electric Company announced to the world that it had successfully created a
diamond. A scientist working for
GE by the name of Dr. Tracy Hall discovered that he could make diamonds
and duplicate the process to
create more. GE began by using a large room-sized 400-ton press to put carbon
under extreme high pressure to
make diamond dust and chips. . The material was not pure enough or large
enough for gems or digital
technology, it did however have other uses such as diamond tipped saws which
made it possible to cut granite
countertops and other hard materials. Companies and inventors have spent
the following decades trying to
make lager and more pure diamonds. In the 1990’s researchers were focused
on two paths to diamonds Brute
force and Chemical Vapor Deposition.
Two ways of making Diamonds
Brute Force
The Gemesis Company in
has been working on and perfecting this procedure in a
warehouse with about two dozen washer sized machines.
These machines use a mixture of temperature and pressure to
grow diamonds from a small “diamond seed” (a small
sliver of natural diamond). Inside the chamber the seed is
bathed in a molten solution of graphite and a proprietary
metal-based catalyst at 1,500 degrees Celsius and 58,000 atm
of pressure. The carbon slowly precipitates onto the
diamond seed in less than three and a half hours a 2.8-carat
rough yellow diamond (gem quality) grows this size of
diamond can yield a gem larger than 1.5-carat cut and
polished.
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1.
Put metal solvents and graphite in ceramic
growth chamber. Insert diamond seed (Diamond
chip or dust) at bottom of chamber and put growth
chamber in center of compression sphere.
2.
Push oil
into top layer of sphere, creating pressure against steel anvils. Intense
pressure is transferred through anvils and onto growth chamber. Even with
minimal pressure at surface, force at center reaches 58,000 atmospheres.
carbon atoms
Giacomo Marchesi
3. Turn
on a current wired to one end of ceramic chamber which will raises temperature to
2,300 degrees Fahrenheit. Heat and pressure cause graphite - pure carbon - to
atomize. Freed carbon drawn to cooler end of chamber bonds to diamond seed,
crystallizing layer by layer.
4.
Wait for about 36 hours or 3 days or
more.
5.
Take out growth chamber and smash it,
pull out stone. Cut and polish to make sparkling diamond gem.
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IN THE ROUGH To grow its
gem-quality yellow diamonds (a rough one is shown above), Gemesis uses
washing-machine-sized crystal-growing chambers to reproduce the high
pressures and high temperatures that nature relies on.
GEMESIS PHOTOS |
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Chemical Vapor
Deposition
The Apollo Company has focused on Chemical Vapor Deposition or
CVD a combination of carbon gases,
temperature and pressure that recreates the environment
diamonds were original created under thousands of
years ago. Atoms from the vapor land on a diamond chip
placed the chamber. The vapor particles attach to the
structure of the diamond growing the diamond atom by atom
into a considerably larger diamond. This process
can make diamonds that are clear and utterly pure. The CVD
process can be manipulated by putting boron to
allow the diamond to conduct a current which allows the
diamond to become a conductor.
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“LET
IT RAIN To make diamond by chemical vapor deposition, hydrogen gas and methane
are flowed through a chamber containing a substrate. Heat or a
microwave-generated plasma is used to split hydrogen gas into atomic
hydrogen, which then reacts with methane to give methyl radical and hydrogen
gas. The carbon-containing radical species eventually deposit as diamond onto
the substrate.” Joshua Davis. |
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Photo by Joshua Davis |
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1. Place
diamond wafers on pedestal. Depressurize chamber to one-tenth of an atmosphere.
2.
Inject hydrogen, natural gas (CH4) into chamber add heat using a microwave
beam. At 1,800 degrees
Fahrenheit, electrons separate from nuclei, forming plasma.
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3.
Let it rain.
Freed carbon precipitates out of plasma cloud
and is deposited on wafer seeds.
4.
Let
it grow. Wafer seeds gradually become diamond minibricks, building up at half a
millimeter a day.
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5.
Open chamber and remove diamond brick.
Slice into wafers for semiconductors or cut and
polish to make gems. (Joshua Davis)
Future of
Diamonds and possibilities
The
possibilities for
man-made diamonds are endless this material is the hardest; it will expand in
heat
and will not deteriorate and is chemically inert and
optically transparent. The use of man-made diamonds is endless
and it has been said that this invention can revolutionize
the industrial world like steel and transistors did decades ago.
Jewelry
The introduction of the man-made diamond into the mined
diamond market has caused a serious reaction by
the number one mined diamond dealer in the world the DeBeers
cartel. The cartel has implemented the Gem Defensive
Program in which testing machines have been sent out to the
largest national gem laboratories. Traditionally these
laboratories have been used to certify and analyze color,
clarity and size now they are being asked to distinguish
between a mined diamond and a man-made diamond. These has
proven to be a most difficult feat as both diamonds
have the same chemical make up and reflect light in the same
way. There has not been a proven 100 percent method
of distinguishing one from the other.
The
DeBeers cartel and the Jewelers Vigilance Committee have pressured the Federal
Trade Commission to
force companies like Gemesis and Apollo to label their man-made
diamonds as synthetic. Gemesis is currently
developing a marketing campaign in which the diamonds are
called “cultured-diamonds” hoping that
the public
would be more willing to except these diamonds as they do
the cultured pearl the campaign it to intice the customer
to buy the man-made diamond and make them sound almost
superior to mined diamonds.
Technology
The
idea of being able to use diamonds as optical storage will allow the use of
lasers to store data in 3D
patterns, cramming huge amounts of information in tiny
space. The use of a diamond wafers as a replacement to
silicon ones in computers will allow scientist makes
microchips which run even faster and heat conduction in no
longer an issue.
References:
Yarnell, Amanda The Many Facets of Man-Made Diamonds
Chemical and Engineering News, Cover Story,
http://pubs.acs.org/cen/coverstory/8205/8205diamonds.html
Davis, Joshua The New Diamond Age Wired Magazine
http://www.wired.com/wired/archive/11.09/diamond.html
Maney, Kevin Man-made diamonds sparkle with potential
http://www.usatoday.com/tech/news/techinnovations/2005-10-06-man-made-diamonds_x.htm
Mulrean, Jennifer Man-made diamonds: a girl's new best
friend? MSN Money
http://moneycentral.msn.com/content/SavingandDebt/P97816.asp
Gemisis
http://www.gemesis.com/news.htm
Apollo Diamond
http://www.investmentu.com/IUEL/2003/20030818.html
http://docbug.com/blog/archives/000028.html
Tracy Hall
http://www.htracyhall.org/histsynth.html
Photo Credits:
http://www.wired.com/wired/archive/11.09/diamond.html